[s] Use shell's printf's %q for escaping if possible
[urxvt] Use new tabbedex features and remove unused modules
[xlocker] Use slock if present
[emacs] Remove `use-empty-active-region' definition

That variable is defined only for backward compatibility but in
the file it is only used in `use-region-p' function which is also
defined for backward compatibility.  It's much easier to just drop
the variable and assume its nil in the `use-region-p' function.
[emacs] Improve documentation plus some other small code changes
[emacs] Refactor `seq-times' macro
[emacs] Move Emacs configuration to emacs/ directory
[emacs] Move faces to customize file

Customize file is now included in the repository, and its name
has been changed to custom.el so Emacs knows its Emacs Lisp when
it opens it.